In recent years, surface-mountable packages which permit surface mounting of semiconductor devices on a wiring board are frequently employed for higher density integration of the semiconductor devices on the wiring board. BGA (Ball Grid Array) packages are known as typical examples of such surface-mountable packages.
A semiconductor device employing a BGA package includes a semiconductor chip mounted on an interposer. The interposer includes an insulative substrate of a glass epoxy resin. Provided on one surface of the insulative substrate are an island on which the semiconductor chip is bonded, and internal terminals respectively electrically connected to pads on a front surface of the semiconductor chip via bonding wires. Provided on the other surface of the insulative substrate are ball-shaped external terminals for electrical connection to lands (electrodes) provided on a mount board (printed wiring board). The insulative substrate has through-holes extending therethrough from the one surface to the other surface thereof. The through-holes are filled with a metal material. The internal terminals on the one surface of the insulative substrate are respectively electrically connected to the external terminals on the other surface via metal portions provided in the through-holes.
Patent Document 1: Japanese Unexamined Patent Publication No. 2001-181563